Portable handheld work apparatus with internal combustion engines include liquid vessels for operating substances such as lubricating oil or fuel. Attention has to be given especially in a fuel tank that no higher underpressure is built up in the fuel tank when taking fuel therefrom because this can disadvantageously affect the mixture formation of a membrane carburetor supplied from the fuel vessel. The membrane carburetor makes the air/fuel mixture available which is needed for the operation of the engine.
A venting valve is known from German patent publication 100 12 893. This venting valve has a valve housing made up of a base body and a valve cover. A valve member in the form of a valve plate is arranged between the base body and the valve cover. The valve plate controls a pressure compensating channel connecting the vessel interior space to the vessel exterior.
The construction is so configured that the valve housing is held together by a cover cap which engages over the valve cover and is fixed with an attachment section on the base body.
This known venting valve has been proven in practice and ensures a pressure compensation in the fuel vessel over many operating hours without the problem of fuel exiting when there is an overpressure. However, forces can act on the cover cap when there is an improper use and negligent use during work which can lead to an unwanted separation of the cover cap from the base body of the valve housing. The venting valve is then inoperable and operation with the work apparatus must be ended.